Paraensidimerins E and F, two new alkaloids from the heartwood of Euxylophora paraensis (Rutaceae), have been shown to be the heptacyclic bis-quinolin-2-one derivatives (1c) and (1d); they are stereoisomers of paraensidimerins A (1a) and C (1b) which have previously been isolated from the same plant, and form part of a new group of alkaloids isolated from this plant, the other two members of which are paraensidimerins G (2) and B (3).